Circuit breaker



G. O. WILMS CIRCUIT BREAKER Oct. 30, 1934.

Original Filed Nov. l, 1929 Patented Oct. 30, 1934 PATENT oFFlc CIRCUIT BREAKER Gustav O. Wilms, Milwaukee, Wis.,

assignor, by

mesne assignments, to Allen-Bradley Company, Milwaukee, Wis., a. corporation of Wisconsin Application November 1, 1929, Serial No. 403,989 Renewed March 26, 1934 14 Claims.

This invention relates to a thermally operable self-soldering circuit breaker.

The circuit breaker to which the invention applies in particular has a switch to control an electric circuit, an electric heater for connection into the circuit to be controlled, a heat conductor to conduct heat from the heater, a latch xed on the conductor by a fusible binder, and a catch to engage the latch and hold the switch closed.

Such a circuit breaker is disclosed in my copending application, Serial No. 226,386, led October 15, 1927, of which this application is a continuation as to matter common to both applications.

An object of the rinvention is to provide a circuit breaker which is compact and eiiicient.

Another object is to provide a circuit breaker which is self-contained.

Another object is to provide a circuit breaker which is particularly adapted for domestic use.

Another object is to provide a circuit breaker which is simple in construction and which may be economically manufactured.

According to the invention as ordinarily embodied, the circuit breaker has an automatically opening plunger switch, an electric heater connected in circuit with the switch, a stationary heat conductor to conduct heat from the heater, a latch xed on the heat conductor by a fusible binder, and a catch to engage the latch and hold the switch closed.

The invention further providesv a thermally operable circuit breaker having a link pivoted to the plunger of the switch and carrying a catch to engage the latch.

A circuit breaker embodying the invention is shown in the accompanying drawing in which the views are as follows:

Fig. 1 is a ytop plan View with the top cover plate omitted,` showing the circuit breaker closed and indicating the open position thereof by dotted lines.

Fig. 2 is a front view with the casing shown in section.

Fig. 3 is a bottom plan view with the bottom cover plate omitted.

The circuit breaker mechanism is arranged in and carried by a casing 1 having the top and bottom thereof closed by cover plates 2 and 3, respectively, which are removably secured in place by through bolts 4 and 5.

. The casing 1 is preferably made of insulating material and provided with terminals 6 and 7 upon the outside of the rear wall thereof for con- (Cl. 20D-124) necting the circuit breaker into the electric circuit to be controlled. v

A heater terminal 8 and a stationary switch contact 9 are arranged upon the inside of the casing 1 and electrically connected to or formed integral with the terminals 6 and 7, respectively.

A heater 10, shown as a coil of resistance wire, has one terminal connected to the heater terminal 8 and the other terminal thereof connected to the heater terminal 11 which is velectrically connected to or formed integral with a stationary switch contact 12.

'I'he contacts 9 and 12 are normally bridged by a movable contact 13 which is slidably arranged upon the stem 14 of a plunger 15 made of insulating material and adapted to be reciprocated to open and close the circuit to be controlled.

The forward end of the plunger 15 is slidable through an opening 16 in the front Wall of the casing 1 and the stem 14 is slidable in a guideway 17 in the rear wall of the casing 1 and in a boss 18 formed integral therewith.

A -coil spring 19 is arranged upon the stem 14 and normally urges the contact 13 against the contacts 9 and 12 when the plunger 15 is moved inwardly.

A stop 20 is fixed on the stem 14 and adapted to move the contact 13 out of engagement with the contacts 9 and 12 when the plunger 15 is moved outwardly.

A linlr 21 is pivoted at one end by a pin 22 to the plunger 15 and at the other end by a pin 23 to a support 24 which is carried by or formed integral with the casing 1.

The plunger 15 is urged outwardly to open the circuit by a spring 25 which is arranged upon the pin 23 and has one end 26 thereof in engagement with the `end wall of the casing 1 and the other end 27 thereof arranged in an aperture in the link 21.

The contact 13 is normally held in engagement with the contacts 9 and 12, against the action of the spring 25, by a catch or pawl 28 which is pivoted on the link 21 and urged by a spring 29 into engagement with a latch or ratchet wheel 30 xed by a fusible binder 31, such as solder, upon a spindle or heat conductor 32 carried by the support 24 and heat insulated therefrom by a heat insulating bushing 33.

'Ihe heat conductor 32 is made of highly conductive material, such as copper, and has the lower end thereof arranged in intimate .association with, but preferably spaced from, the heater 10.

The heater 10 is selected in accordance with the motor to be protected and, when in the form of a coil, may have the heat characteristics thereof varied by varying the gauge of the resistance wire employed, the diameter of the coil relatively to the diameter of the heat conductor 32, the number of turns in the coil, or a combination of such variables.

Whenever an overload occurs which is of such proportions or which continues for such a length of time that further operation would result in damage to the motor, the heat generated by the heater 10 under the influence of the overload is transferred by radiation to the conductor 32 and conducted thereby to the binder 31, fusing the same and permitting the spring 25 to rotate the latch 30 and raise the plunger 15 to open the circuit and stop the motor.

The binder 31 then quickly hardens and xes the latch 30 tothe conductor 32 again so that the vplunger l5 may be moved inwardly to close the circuit and restart the motor, the catch 28 reengaging the latch 30 and the spring 19 compensating for any variation in the position of the teeth thereof. u

The heater should have heat characteristics corresponding to the characteristics of the motor or other appliance to be protected so that the same may operate under harmless overloads, operate for predetermined periods under overloads which would eventually damage the motor or appliance and be disengaged from the circuit almost instantly when subjected to a prohibitive overload.

The circuit breaker may be adapted to protect any motor by simply providing the same with a heater having heat characteristics corresponding to the characteristics of that motor.

The invention herein set forth is susceptible of various modifications Without departing from the scope thereof as hereafter claimed.

The invention is claimed as follows:-

1. A circuit breaker comprising an electric heater for connection into an electric circuit, a heat conductor having a latch secured upon one part thereof by a fusible binder and another part thereof spaced from said binder and thermally associated with said heater to enable said conductor to conduct heat from said heater to said binder to fuse the same, a support for said heat conductor, an automatically opening plunger switch to control said circuit, a link pivoted to said switch and said support, and a catch carried by said link to engage said latch and hold said switch closed.

2. A circuit breaker comprising an electric heater for connection into an electric circuit, a heat conductor having a latch secured upon one part thereof by a fusible binder and another part thereof spaced from said binder and thermally associated with said heater to enable said conductor to conduct heat from said heater to said binder to fuse the same, a support for said heat conductor heat insulated therefrom, a plunger switch to control said circuit, a spring to open said switch, a link pivoted to said switch and said support, and a catch carried by said link to engage said latch and hold said switch closed against the action of said spring.

3. A circuit breaker comprising an electric heater for connection into an electric circuit, a heat conductor having a latch secured upon one part thereof by a fusible binder and another part thereof spaced from said binderand thermally associated with said heater to enable said conductor to conduct heat from said heater to said binder to fuse the same, a support for said heat conductor arranged between said heater and said latch and heat insulated from said heat conductor, an automatically opening plunger switch to control said circuit, a link pivoted to said switch and said support, and a catch carried by said link to engage said latch and hold said switch closed.

4. A circuit breaker comprising a casing, an electric heater arranged in said casing and adapted to be connected into an electricv circuit, an automatically opening switch arranged in said casing to control said circuit, a plunger slidable in said casing and manually operable to close said switch, a support in said casing, a heat conductor carried by said support and heat insulated therefrom and having a latch secured upon one part thereof by a fusible binder arranged on one side of said support and another part thereof on the other side of said support thermally associated with said heater to enable said conductor to conduct heat from said heater to said binder to fuse the same, and a catch pivotally connected to said plunger and engaging said latch to hold said switch closed.

5. A circuit breaker comprising a casing, an electric heater arranged in said casing and adapted to be connected into an electric circuit, an automatically opening switch arranged in said casing to control said circuit, a plunger slidable in said casing and manually operable to close said switch, a support in said casing, a heat conductor carried by said support and heat insulated therefrom and having a latch secured upon one part thereof by a fusible binder arranged on one side of said support and another part thereof on the other side of said support thermally associated with said heater to enable said conductor to conduct heat from said heater to said binder to fuse the same, a link pivoted to said support and said plunger, and a catch pivoted on said link and engaging said latch to hold said switch closed.

6. A circuit breaker comprising a casing, an

plunger, and a catch pivoted onI said link and engaging said latch to hold said switch closed.

7. A circuit breaker, comprising' a casing, an electric heater arranged in said casing for connection into an electric circuit, a switch arranged in said casing to control said circuit, a plunger slidable in said casing and manually operable to close said switch,'a support carried by said casing, a link having one end pivoted to said support and its other end pivoted to said plunger, a spring to open said switch, a heat conductor having a latch fixed upon one part thereof by a fusible binder and another part thereof spaced from said binder and thermally associated with said heater to enable said heat conductor'to conduct heat from said heater to said binder to fuse the same, a catch carried by said link intermediate the ends thereof, and normally engaging said mehto hold said switch closed.

8. A circuit breaker, comprising a casing, an electric heater arranged in said casing for c'onnection into an electric circuit, a switch arranged in said casing to control said circuit, a plunger slidable in said casing and manually operable to close said switch a support carried by said casing, a link having one end pivoted to said support and its other end pivoted to said plunger, a spring acting upon said link, to open said switch, a heat conductor having a latch fixed upon one part thereof by a fusible binder and another part thereof spaced from said binder and thermally associated with said heater to enable said heat conductor to conduct heat from said heater to said binder to fuse the same, a catch carried by said link intermediate the ends thereof and normally engaging said latch to hold said switch closed.

9. A circuit breaker, comprising a casing, an electric heater arranged in said casing for connection into an electric circuit, a switch arranged in said casing to control said circuit, a plunger slidable in said casing and manually operable to close said switch, a heat conductor having a latch fixed upon one part thereof by a fusible binder and another part thereof spaced from said binder and thermally associated with said heater to enable said heat conductor to conduct heat from said heater to said binder to fuse the same, a support arranged between said heater and said binder to support said heat conductor and heat insulated therefrom, a link pivoted at one end to said support and at its other end to said plunger, a spring to open said switch, and a catch pivoted upon said link intermediate the ends thereof and normally engaging said latch to hold said switch closed.

l0. A circuit breaker, comprising a casing, an electric heater arranged in said casing for connection into an electric circuit, a switch arranged in said casing to control said circuit, a plunger slidable in said casing and manually operable to close said switch, a heat conductor having a latch fixed upon one part thereof by a fusible binder and another part thereof spaced from said binder and thermally associated with said heater to enable said heat conductor to conduct heat from said heater` to said binder to fuse the same, a support arranged between said heater and said binder to support said heat conductor and heat insulated therefrom, a link pivoted at one end to said support and at its other end to said plunger, a spring acting upon said link to open said switch, and a catch pivoted upon said link intermediate the ends thereof and normally engagng said latch to hold said switch closed.

ll. A circuit breaker, comprising a support, a switch carried by said support and having its movable contact biased to an initial position, a

link pivotally connected to said movable contact and to said support, a ratchet held by a fusible binder, a pawl carried by said link to engage said ratchet to hold said movable contact in another position, and moans to heat said fusible binder and thereby release said ratchet to release said pawl and allow said movable contact to return to its initial position.

l2. A circuit breaker, comprising a support, a switch carried by said support and having a movable contact biased to an initial position, a heat conductor carried by said support, a ratchet wheel secured upon said heat conductor by a fusible binder, a link pivoted to said movable contact and pivoted to said support, a pawl carried by said link to engage said ratchet wheel to hold said movable contact away from its initial position, and means to heat said heat conductor and fuse said fusible binder thereby permitting said ratchet Wheel to turn to release said pawl and allow said movable contact to return to its initial position.

13. A circuit breaker, comprising a casing, a switch arranged in said casing and having a movable contact biased to an initial position, manually operable means carried by said casing to move said contact to another position, a link pivotally connected at one end to said casing and pivotally connected at its other end to said means for moving said movable contact, a ratchet wheel held in fixed position by a fusible binder carried by said casing, a pawl pivoted on said link to engage said ratchet Wheel to hold said movable contact in its other position, and an electric heater arranged in said casing to heat and fuse said fusible binder Yand thereby permit said ratchet wheel to turn to release said pawl and allow said movable contact to return to its initial position.

14. A circuit breaker, comprising a casing, a support in said casing, a heat conductor carried by said support and heat insulated therefrom, a latch secured upon one part of said heat conductor by a fusible binder and arranged on one side of said support, an electric heater arranged in said casing and thermally associated with said heat conductor on the other side of said support, a cover on said casing and arranged to be removable to allow access to said heater for adjusting it, a switch arranged in said casing and having its movable contact biased to an initial position, a plunger slidable in said casing and manually operable to move said contact to another position, and a pawl connected to said plunger and arranged to engage said latch to hold said movable contact away from its initial position.

GUSTAV O. WILMS. 

